The invention relates generally to medical imaging and, in particular, to the acquisition and/or reconstruction of images using computed tomography.
Non-invasive medical imaging technologies allow a caregiver to obtain and view images of the internal structures and organs of a patient without performing surgery or other invasive procedures. In particular, technologies such as X-ray radiography, computed tomography (CT), tomosynthesis, magnetic resonance imaging (MRI), ultrasound, C-arm angiography, positron emission tomography (PET), and single positron emission computed tomography (SPECT) use various physical principles to create two-dimensional and/or three-dimensional representations of the interior of the human body. For example, in those imaging modalities utilizing X-rays, the principle of operation typically involves assessing the differing attenuation of the X-rays by the patient's body at one or more angles. Based upon the differential attenuation attributable to different tissues, a two- or three-dimensional image may be reconstructed that accurately depicts the internal structure of the patient. Different imaging modalities apply differing physical principles, but in each case a useful image derived using some property of the patient's body is produced.
In CT, one or more X-ray sources are typically employed which are rotated about a patient (or other object undergoing imaging) to collect X-ray attenuation data at a variety of angular positions. For scans in which data is collected over a wide viewing area (i.e., where the X-ray beam is emitted as a wide cone) attenuation data may be missing or incomplete due to longitudinal data truncation at the edges of the detector. Likewise, certain types of image artifacts (e.g., cone beam artifacts) may be introduced in systems where X-rays impact the detector at wide cone angles. Likewise, image artifacts may occur when the X-ray beam is not wide enough to cover the entire cross-section of the object being scanned, resulting in transaxial data truncation. Such artifacts and missing data may reduce the usefulness of images acquired using such systems.